Raid 0 is striping (spliting data between 2 or more discs to increase read / write speeds), this is a technology you can use on ANY discs, whether these be IDE, SATA, SAS, FC etc etc,
Wont really make much difference the the average home user IMO, you just double your chances of loosing data.
Reference the 8GB, WHY WHY WHY?
What applications are you running that are going to make use of that memory?
Anything more then 2GB is overkill IMO
And driver support for Windows 64bit OS's is wank, your guna have exactly the same problems whether it be XP 64 or Vista 64,
Please dont take this the wrong way, but if you dont understand basic raid principles, and did'nt know about the 3.5gb (ish) limit on 32bit Windows, then it suggests to me that your just chasing numbers for pub chat